Vtol flight unit



Oct. 4, 1966 J. w. MILLER ETAL VTOL FLIGHT UNIT 5 Sheets-Sheet 1 Filed Feb. 28, 1964 Mame;

INVENTORS ATTOl-PA/EVJ Oct. 4, 1966 J. w. MILLER ETAL VTOL FLIGHT UNIT 3 Sheets-Sheet 2 Filed Feb. 28, 1964 2 W Burger d W M///@/* H074 ye H #0004 Fremon INVENTORS Oct. 4, 1966 J. w. MILLER ETAL VTOL FLIGHT UNIT 3 Sheets-Sheet 5 Filed Feb. 28, 1954 Fremonz VV. Burger 4/0/7768 W. /l/////6/ Harvey Hove/e INVENTORS United States Patent 3,276,723 VTOL FLIGHT UNIT James W. Miller and Harvey H. Houde, San Antonio, and Fremont W. Burger, Houston, Tex., assignors to Astro Kinetics Corporation, a corporation of Texas Filed Feb. 28, 1964, Ser. No. 348,045 2 Claims. (Cl. 244-12) This invention relates to new and useful improvements in flight units, and particularly to flight units which are adapted to take-01f and land substantially vertically.

In the past, efforts have been made to provide flight units adapted to take-off and land substantially vertically. The present-day helicopter is typical of suchprior efforts. Although such prior units are workable, they provide a relatively low lift force, primarily due to the means by which the prior units obtain such lift force.

It is an object of this invention to provide a new and improved flight unit adapted for substantially vertical take-off and landing.

An important object of this invention is to provide a new and improved flight unit wherein a fan or other means is provided in a bell shroud for moving air relative to the shroud for creating a lift force.

Another object is to provide a new and improved flight unit having means therewith for creating a combination of different lifting forces so that the magnitude of such combined forces is suflicient to provide for sustained vertical and horizontal flight.

A further object of this invention is to provide a new and improved flight unit wherein a fan, propeller or other high velocity air-moving means is mounted in a shroud for directing moving air over the upper surface of the shroud, through the shroud and then over an airfoil to create multiple lifting forces which together effect vertical and horizontal flight of the unit.

Still another object of this invention is to provide a new and improved flight unit wherein an external shroud is mounted around an inner diffuser for diffusing air substantially radially over an airfoil for obtaining multiple lifting forces on the unit.

Yet a further object of this invention is to provide a new and improved flight unit having a new and improved control assembly therewith, including elevons for changing the attitude of the unit.

A particular object of this invention is to provide a new and improved flight unit having torque-control means for controlling torque forces acting on the unit to effect a control on the horizontal directional movement of the unit.

The preferred embodiment of this invention will be described hereinafter, together with other features thereof, and additional objects will become evident from such description.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown, and wherein:

FIG. 1 is an elevation, partly in section, illustrating the preferred embodiment of the present invention;

FIG. 2 is a plan view illustrating in particular details of the control mechanism for controlling the attitude and the horizontal component of directional movement of the flight unit;

FIG. 3 is a view, partly in elevation and partly in section, illustrating a fragmentary portion of the flight unit of FIGS. 1 and 2, and illustrating in particular the details of construction of one of the internal rudders of such flight unit; and

FIG. 4 is a fragmentary view illustrating further details of the control mechanism which is preferably employed with the flight unit of this invention.

In the drawings, the letter F designates generally the support frame of the flight unit. An air-moving means M is mounted on said support frame F and is surrounded by an annular shroud S for controlling the air flow and creating air lift forces as will be further explained. An inner diffuser D is disposed inwardly of the shroud S, with means being provided for supporting both the diffuser D and the shroud S on the support frame F, as will be further explained in detail. An annular airfoil A is disposed below the shroud S for providing an additional air lift force as the air which is discharged from the shroud S passes over such airfoil A. Also, some of the air which is discharged from the shroud S is directed inwardly of the airfoil A for creating a static thrust and therefore an additional air lift force. As will be explained more in detail, the flight unit of this invention has a plurality of air-lifting forces acting thereon, preferably four in number, in order to provide sustained vertical movement of the flight unit as well as horizontal flight.

Considering the invention more in detail, the support frame F, in its preferred embodiment, includes four substantially vertical or upright frame members 10, each of which is preferably formed of tubular stock or pipe and which are joined together at their upper ends by laterally extending frame members 11 (FIGS. 1 and 2), each of which is also preferably formed of tubular stock or pipe. Laterally extending frame members 12 and 14, which preferably correspond with the frame members 11, are connected to the lower portions of the uprights 10. Such frame members 11, 12 and 14 are secured to the vertical frame members 10 by welding or other suitable securing means.

A plurality of landing legs L, preferably four in number, are secured to the vertical frame members or uprights 10 by welding or other suitable connection means. Preferably the landing legs L extend diagonally outwardly from each of the vertical or upright members 10 so as to provide a relatively large base for engaging the ground G or other surface upon which the unit lands or is placed at rest.

To rigidify the support frame F, one or more diagonally extending braces 15 is provided. Such brace or braces 15 is formed of tubular stock or other material which is welded -or otherwise secured to the upper end of one of the vertical uprights 10 and the lower end of another of the vertical uprights 10. Also, the support frame F preferably has a fuel tank 16 welded or otherwise mounted thereon and which preferably forms the back portion of a seat 17 for the operator of the flight unit of this invention (operator shown in dotted lines). A suitable headrest 18 may also be mounted on the support frame F for the comfort of the operator if desired. The tank 16 is connected in a conventional way by hoses (not shown) with the engine of the air-moving means M. It will be appreciated that additional tanks for the fuel may also be provided if necessary for increasing the range of operation of the flight unit of this invention.

The air-moving means M of this invention may be of any suitable type such as a fan, propeller, counter-rotating propellers, a unit with multiple blades, or any other suitable air-moving means. As illustrated in the drawing, the air-moving means M includes a gasoline engine 20 which has four inclined leg supports 21 Welded, bolted or otherwise secured thereto and also secured to the upper end of the support frame F. In the specific form of the air-moving means M illustrated in the drawings, a propeller or rotatable fan blade 22 is rotatably mounted at the upper end of the engine 20 and is rotated by the engine 20. As will be understood by those skilled in the art, the shape of the propeller 22 may be varied, but such shape must be such as to produce a downward flow of air when the blade 22 is rotated as indicated by the arrows in FIG. 1.

The diffuser D has an external annular wall 24 which is curved downwardly and outwardly from a point below the rotating blade 22. Although the diffuser wall 24 is not truly conical, it generally resembles a conical shape and for the purposes of description herein is described as being substantially conical. The upper end 24a of the wall '24 may be open as shown in FIG. 1, or it may be closed if desired. In any event, the upper end 24a of the diffuser D is disposed in close proximity to the rotating propeller blade 22 so that the maximum amount of air is moved externally of the wall 24. The wall 24 may have suitable openings 24b and 240 therethrough through which portions of the gasoline engine or other power source may extend in the event the shape of the wall 24 does not confine such engine 20 or other suitable power means.

An internal laterally extending reinforcing plate 25 is provided within the wall 24 with its outer annual edge 25a welded or otherwise secured to the internal surface of the wall 24. Such plate 25 preferably rests upon the upper frame members 11 and suitable openings 25b are provided through which the support legs 21 extend. The diffuser D is further supported on the support frame F by a plurality of diagonally extending support ribs 27, each of which is preferably welded or otherwise secured to one of the vertical support members 10 and also to the lower side of the reinforcing plate 25. In order to reduce the weight of such structural ribs 27, holes 27a are preferably provided as illustrated in FIGS. 1 and 3. In the usual case, there are therefore four of such structural rib supports 27 spaced 90 degrees from each other. Each of the support ribs 27 preferably extends outwardly beyond the outer annular periphery of the wall 24 for connecting to the airfoilA and the shroud S, as will be more fully explained (FIG. 3).

The inner diffuser D is provided with four elevons 28, 29, 30 and 31 (FIGS. 1 and 2) in the preferred form of the invention. Each of such elevons is pivotally connected to the wall 24 by any suitable type of hinge 35 which permits movement backwardly and forwardly, as will be more fully explained.

The shroud S has an upper airfoil surface 36 over which air is caused to pass at a relatively high velocity by the air moving means M to provide an air lift force on the underside of such airfoil surface 36. Such airfoil surface 36 surrounds the upper end 36a of the shroud S and it merges with an intermediate tubular portion 37 within which the blade or propeller 22, or other suitable air-moving means is disposed. The shroud S also has a downwardly extending outwardly flared lower portion 38 which extends from the intermediate or central tubular portion 37 and which generally conforms in shape to the wall 24 of the inner diff-user D. For maximum efliciency, the outer periphery 36b of the airfoil 36 should not have a greater diameter than five times the diameter of the intermediate portion 37 at the intake opening lying in th plane of rotation of the propeller or other air-moving means 22. Also, the area of the annular discharge 38a between the outwardly extending portion 38 of the shroud S and the wall 24 of the diffuser D should preferably be approximately the same as the area at the air inlet lying in the plane of the propeller 22 or other air-moving means within the shroud S.

The air which discharges through the outlet or dis charge opening 38a at the lower end of the shroud S is directed outwardly over the external surface of the airfoil A and is also directed inwardly thereof as indicated by the arrows in FIG. 1. It should be noted that the airfoil A is maintained in a fixed relationship to the wall 24 of the diffuser D and the outwardly flaring portion 38 of the shroud S, preferably by having its upper portion welded or otherwise secured to the upwardly extending extension 40 of each support rib 27. Thus, each extension 40 has a suitable notch 40a formed therein for receiving the upper portion of the airfoil A which is welded or otherwise secured the-rein. It is also to be noted that the upper portion or edge 48b of the extension 40 is welded or otherwise secured to the lower surface of the outwardly extending flared portion 38 to integrally connect the shroud S to each rib 27 and thus to the support frame F.

The upper portion of the rib extension 40 which is disposed between the wall 24 and the outwardly flared portion 38 for each of such rib supports 27, serves as an anti-torque plate. For this purpose, the extreme upper portion 400 of each extension 40 is slightly curved as best seen in FIG. 2. Such curvature is preferably of the magnitude of five degrees at the upper portion 400 but is otherwise radial. Such curvature in the upper portion 480 offsets any tendency of the unit to rotate due to a reaction force of the air being moved downwardly by the air-moving means M with a slight amount of rotation. Thus, as viewed in FIG. 2, assuming there is a slight reaction force on the shroud S tending to move the unit clockwise by reason of the slight rotational movement of the air flowing downwardly from the air-moving means M, the curved portions 400, when contacted by the slightly rotating air, will offset such reaction force and maintain the entire unit in a stable non-rotative condition. Of course, it will be understood that if the air-moving means M includes counter-rotating propellers so that there is no reaction force tending to rotate the unit in either direction, such slight curvature 400 on each anti-torque extension 40 may be unnecessary.

In some instances, it is desirable to control the rotational position or the horizontal component of directional movement of the flight unit by the use of internal rudders 41 (FIGS. 1-3). Each rudder 41 is mounted for pivotal movement on a pivot rod 42 mounted in suitable bearings or guides 42a and 42b. The lower end of the pivot rod 42 has an operating bar 420 (FIG. 3) thereon which is actuated for pivoting the internal rudder 41 as will be explained in detail hereinafter. In the preferred case, two of such rudders 41 are provided at diametrically 0pposite positions as illustrated in FIG. 2 and they are operable together for effecting a rotational or turning movement of the entire flight unit as will be more fully explained.

In some instances, it is desirable to also have an external rudder 45 (FIGS. 1 and 2) which is pivotally mounted at hinge or pivot 46 to a connecting plate 47 which extends over the external surface of the airfoil A and is welded or otherwise secured between the shroud S and the diffuser D as best seen in FIG. 1. An outwardly extending control rod 45a is provided on the rudder 45 for controlling the movement and position of the rudder 45, as will be explained.

For controlling the movement of the various elevons 28, 29, 30 and 31, it is preferable to provide a control arm or column 50 (FIGS. 1 and 4) which is pivotally connected to the support frame F by a pivot pin 51 or other suitable pivotal connection means. As viewed in FIG. 1 the pivot pin 51 permits a pivotal movement of the control bar or column 50 forwardly (left in FIG. 1) and rearwardly (right in FIG. 1) as desired by the operator. The forward elevon 28 is connected to the control rod or arm 50 by a push-pull rod 52 which has a pivotal connection 52a to the elevon 28 and a pivotal connection 52b to the rod or column 50. Similarly, the rear elevon 28 is connected to the column 50 by a push-pull rod 53 which has a pivotal connection at 53a to the elevon 29 and a pivotal connection 53b to the column 50. Thus, as the column 50 is moved forwardly (to the left as viewed in FIG. 1) the rod 52 pushes the elevon 28 forwardly while the rod 53 pulls the elevon 29 forwardly, both moving together. By moving the elevon 28 forwardly, the area between such elevon 28 and the inner surface of the outwardly flaring portion 38 of the shroud S is restricted, causing a reaction force downwardly on such elevon 28 to tilt the forward portion of the entire flight unit downwardly to thereby change its attitude with respect to the ground level.

On the other hand, when the control rod or column 50 is moved rearwardly (or the right as viewed in FIG. 1) the push-pull rod 53 is pushed to move the rear elevon 29 rearwardly while the push-pull rod 52 is pulled to move the elevon 28 rearwardly, thereby creating a restriction between the elevon 29 and the shroud S which causes a downward tilting of the rearward portion of the flight unit with respect to ground level.

For controlling the movements of the side elevons 30 and 31, an endless cable 54 (FIGS. 1, 2 and 4) is provided which is operably connected with push-pull rods 55 and 56 for the elevons 30 and 31, respectively. The cable 54 extends around a pulley or drum 57 which is connected with a steering wheel or handle 58 so that an operator may move the drum 57 by a manipulation of the steering wheel or handle 58 to thereby effect movements of the cable 54. The cable 54 extends upwardly around pulleys or guide rollers 59 and then is guided in a lateral plane at the upper end of the support frame F by pulleys 60 disposed at each corner of the support frame F (FIG. 2) A pivoted bell crank level 61 is mounted on one of the upper laterally extending frame members 11 for pivoting about a pivot pin 61a. The outer portion 61b of the bell crank lever 61 is secured to the cable 54 for movements in response thereto. The inner end 610 of the bell crank lever 61 is pivotally connected to the push rod 55. The push-pull rod 55 is itself pivotally connected at its outer end 5511 to the lower portion of the elevon 30.

The push-pull rod 56 is similarly connected to the cable 54 through a bell crank lever 62 which is pivoted at 6211, connected to the cable 54 at 62b and connected to the rod 56 at pivot 620. The rod 56 is likewise pivoted at 56a to the elevon 31.

With such construction, it will be understood that as the operator turns the steering handle 58, so as to effect a movement of the cable 54 in a generally clockwise movement as viewed in FIG. 2, the push-pull rod 55 is moved to pivot the elevon 30 outwardly while the push-pull rod 56 is pivoted to pull the elevon 31 inwardly. Upon a movement of the cable 54 in a generally counterclockwise direction as viewed in FIG. 2, the opposite movements of the elevons 30 and 31 will be produced. Thus, the elevons 30 and 31 are moved simultaneously or together in the same direction so as to cause the flight unit to move either downwardly to the right or downwardly to the left, as controlled by the steering wheel or handle 58. Thus, all four of the elevons 28, 29, 30 and 31 are readily controlled manually by the operator of the flight unit.

In the preferred form of the invention, the control of the internal rudders 41 and the external rudder 45 is obtained through two foot pedals 70 which are preferably operated by the feet of the operator. Such pedals 70 are preferably interconnected by an endless balance cable 71 which is secured to each of such pedals 70 at connection points 70b (FIG. 2) and which extends around pulleys or guide rollers 72 and 73. Thus, as the left pedal 70 is pushed downwardly so that its lower portion below the pivot 70a pivots downwardly, the portion of the right pedal 70 below its pivot 70a moves upwardly. Similarly, when the right pedal 70 is pivoted downwardly, the left pedal 70 is pivoted upwardly.

Rudder cables 74 and 75 are also connected to the pedals 70 at the connection points 7012 or other similar connection points. As best seen in FIG. 1, the cable 75 is passed rearwardly from the left pedal 70 to a guide pulley 76 and then is passed upwardly over a guide pulley 77. The cable 75 then extends rearwardly to one end of the pivot pin or rod 45a. The cable 74 is connected and is directed in the same manner as described in connection with the cable 75, one of thte pulleys '78 being illustrated in FIG. 2, which pulley 78 corresponds with the pulley 77 for the cable 75, and it will be understood that a pulley corresponding to the pulley 76 is also provided for the directional control of the movement of the cable 74. The rearward end of the cable 74 is connected to the pivot pin or rod 45a. Thus, by moving the cable 74 forwardly (to the left in FIG. 2) the cable 75 is moved rearwardly as the pivot rod 45a pivots in a counterclockwise direction as viewed in FIG. 2. Such movement shifts the rudder 45 about the pivot 46 so that its outer end moves upwardly as viewed in FIG. 2. It will be appreciated that when the cable 75 is pulled forwardly, the reverse movement of the external rudder 45 is produced.

For operating the internal rudders 41 in conjunction with the external rudder 45, a short cable 80 is connected to one end of the pivot bar 420 on one of the internal rudders 41. The other end of the cable 80 is secured at a fixed point 75a to the cable 75 so that as the cable 75 moves forwardly (left in FIG. 2), such movement is transmitted to the cable 80, pulling the pivot bar 420 to pivot same in a clockwise direction as viewed in FIG. 2. Similarly, a cable 81 is connected to one end of the other pivot bar 420 on the' other internal rudder 41 illustrated in FIG. 2. The opposite end of the cable 81 is secured to the cable 75 at a fixed point such as the connection 75a so that the rearward movements (to the right in FIG. 2) of the cable 75 is transmitted to the cable 81 for pivoting the bar 42c counterclockwise as viewed in FIG. 2. Balance cables 84 and 85 are connected to the opposite ends of the two pivot bars or pins 420 to provide simultaneous coordinated movement of the two internal rudders 41. Thus, when the upper rudder 41 (FIG. 2) is pivoted clockwise by pulling on the cable 80 as the cable 75 moved forwardly, the lower rudder 41 (FIG. 2) is also pivoted clockwise by an equal amount by means of balance cable 84. Also, when the lower rudder 41 (FIG. 2) is pivoted counterclockwise by pulling on the cable 81 as the cable 75 moves rearwardly, the upper rudder (FIG. 2) is also pivoted counterclockwise by an equal amount by means of such balance cable 84. Cable 85 could be omitted in this form of invention if desired.

It will be appreciated that the internal rudders 41 are operable even though the flight unit has no forward or other horizontal component of movement, but the external rudder 45 is effective only during forward or horizontal movement of the unit.

In the operation of the flight unit of this invention, the operator assumes the position indicated in dotted lines in FIG. 1 on the seat 17. It will be understood of course that the support frame F may be enclose-d to protect the operator in flight. Also, to improve the visibility of the operator, it is preferable to provide an airfoil A of a transparent material, or at least an airfoil A having sections of transparent material.

With the operator thus in the seated position illustrated in FIG. 1, the speed of the air-moving means M is developed or increased through the manipulation of suitable controls (not shown) until the air flow from such means M is adequate for lifting the flight unit upwardly from the ground G.

As previously explained, the present invention actually has four principal lifting forces created which are acting upwardly as a unitary combination force for effectively lifting the flight unit of this invention. The first lifting force is created by the rotation of the propeller or other air-moving means M, which creates a low pressure area thereabove. The air above the means M moving over the airfoil surface 36 creates an upward lifting force by reducing the air pressure above such airfoil surface 36. Anotherupward lift force is provided by the substantially radial diffusion of the air over the airfoil A which creates an aerodynamic lift. The fourth lift force is due to the static thrust created by the propeller or other air-moving means as the air is discharged downwardly through the shroud and inwardly of the airfoil A.

During the upward lift by the aforesaid combination action, the elevons 2 8, 29, and 31 are normally maintained in the neutral positions illustrated in the drawings. Also, the internal rudders 41 are in a neutral position in alignment With their corresponding anti-torque plates while the external rudder is in the neutral position illustrated in FIGS. 1 and 2.

When the flight unit has moved upwardly to a suflicient altitude to clear the surrounding buildings and other objects, a horizontal component of movement may be obtained by tilting the flight unit at an angle from the horizontal attitude shown in FIG. 1. Such tilting may be accomplished by moving the control arm forwardly (to the left as viewed in FIG. 1) which moves the elevons 28 and 29 as heretofore described to cause the forward portion of the flight unit to tilt downwardly. When the proper angle or attitude is thus acquired, a component of horizontal force is obtained together with some vertical lifting action. Various changes in the attitude of the unit may be obtained by moving the two pairs of elevons as desired. Also, it will be appreciated that by controlling the speed of the air-moving means and by controlling the attitude of the flight unit, the desired relationship between vertical lift and horizontal movement may be obtained in any given situation.

The horizontal component of directional movement is controlled by the foot pedals 70 as previously explained so as to effect a change in angle of the internal rudders 41 and the external rudder 45. The particular angle at which such rudders are positioned determines the extent and rapidity with which the flight unit changes its horizontal component of directional movement. When the desired horizontal direction is obtained, the rudders 41 and 45 are returned to their neutral positions.

When it is desired to return the flight unit to the ground, the normal horizontal attitude illustrated in FIG. 1 is obtained as nearly as possible, and then the speed of the air-moving means M is reduced so that the gravity force acting on the flight unit slowly and gradually returns the unit to the ground G, with the legs L contacting the ground G with a minimum of impact.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made Within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A flight unit adapted to be used for substantially vertical take-off and landing, comprising:

(a) an annular shroud having an open upper end and an open lower end,

(-b) an air-moving means mounted in said shroud for causing an air flow into said open upper end of said shroud and out of said lower open end thereof for creating a first lifting force,

(c) an airfoil disposed below the lower end of said shroud and over which air flowing from said lower end passes for creating another lifting force,

(d) an inner diffuser member extending into said shroud for diffusing the air outwardly as the air discharges from said open lower end of said shroud and for directing such diffused air over said airfoil,

(e) a plurality of circumferentially spaced elevons pivotally connected to said diffuser member for movement into and away from the air being discharged from said open lower end for changing the attitude of the unit in flight,

(f) said elevons being two pairs, each pair of which has substantially diametrically disposed elevons, (g) a control member pivotally mounted on said diffuser member, and

(h) a control rod extending from said control member to each of said elevons in one of said pairs for pivoting same together.

2. A flight unit adapted to be used for substantially vertical take-off and landing, comprising:

(a) an annular shroud having an open upper end and an open lower end,

(b) an air-moving means mounted in said shroud for causing an air flow into said open upper end of said shroud and out of said lower open end thereof for creating a first lifting force,

(0) an airfoil disposed below the lower end of said shroud and over which air flowing from said lower end passes for creating another lifting force,

(d) an inner diffuser member extending into said shroud for diffusing the air outwardly as the air discharges from said open lower end of said shroud and for directing such diffused air over said airfoil,

(e) a plurality of circumferentially spaced elevons pivotally connected to said diffuser member for movement into and away from the air being discharged from said open lower end for changing the attitude of the unit in flight,

(f) said elevons being two pairs, each pair of which has substantially diametrically disposed elevons, (g) a control member pivotally mounted on said diffuser member,

(h) a control rod extending from said control member to each of said elevons in one of said pairs for pivoting same together, and

(i) control means operably mounted in conjunction with said control member and having connection with the other pair of said elevons for pivoting same together.

References Cited by the Examiner UNITED STATES PATENTS 1,123,589 1/1913 Porter 244 23 2,008,464 7/1935 Nishi 244 73 2,978,206 4/1961 Johnson 2444-73 3,041,009 6/1962 Wharton 244-73 3,107,071 10/1963 Wessels 244-73 FOREIGN PATENTS 15,735 1912 Great Britain.

MILTON BUCHLER, Primary Examiner. *FERGUS S. MIDDLETON, Examiner. R. G. BESHA, L. C. HALL, Assistant Examiners. 

1. A FLIGHT UNIT ADAPTED TO BE USED FOR SUBSTANTIALLY VERTICAL TAKE-OFF AND LANDING, COMPRISING: (A) AN ANNULAR SHROUD HAVING AN OPEN UPPER END AND AN OPEN LOWER END, (B) AN AIR-MOVING MEANS MOUNTED IN SAID SHROUD FOR CAUSING AN AIR FLOW INTO SAID OPEN UPPER END OF SAID SHROUD AND OUT OF SAID LOWER OPEN END THEREOF FOR CREATING A FIRST LIFTING FORCE, (C) AN AIRFOIL DISPOSED BELOW THE LOWER END OF SAID SHROUD AND OVER WHICH AIR FLOWING FROM SAID LOWER END PASSES FOR CREATING ANOTHER LIFTING FORCE, (D) AN INNER DIFFUSER MEMBER EXTENDING INTO SAID SHROUD FOR DIFFUSING THE AIR OUTWARDLY AS THE AIR DISCHARGES FROM SAID OPEN LOWER END OF SAID SHROUD AND FOR DIRECTING SUCH DIFFUSED AIR OVER SAID AIRFOIL, 